Demonstrators flooded the airport's arrival and departure areas during the sit-in rally, stranding all travelers at the airport. Only flights that had already begun boarding or those cleared for landing were allowed to use runways at the airport.

"All other flights have been canceled for the rest of today," the airport statement said.

Here are eight incredible pictures showing the scale of the shutdown.

Protesters surround banners that read "Those charge to the street on today is brave!," center top, and "Release all the detainees!" during a sit-in rally at the arrival hall of the Hong Kong International airport in Hong Kong on Aug. 12, 2019. Hong Kong airport suspended check-in for all remaining flights Monday due to ongoing pro-democracy protest in the terminal.(Photo: Vincent Thian, AP)

Protesters wave flags as they occupy Hong Kong Chek Lap Kok International Airport in Hong Kong on Aug. 12, 2019. Hong Kong has been gripped for weeks by mass protests, which began in June 2019 over a now-suspended extradition bill to China and have developed into an anti-government movement.(Photo: Jerome Favre, EPA-EFE)

Protesters rest among signs at Hong Kong's International airport during a protest against the police brutality and the controversial extradition bill.(Photo: Philip Fong, AFP/Getty Images)

Travelers gather near a flights information board at the Hong Kong International airport.(Photo: Vincent Thian, AP)

Protesters line up for a train at an airport station after a protest.(Photo: Philip Fong, AFP/Getty Images)

Australian Penny Tilley, center, reacts next to stranded travelers at the closed check-in counters at the Hong Kong International Airport.(Photo: Kin Cheung, AP)

Protesters occupy the departure hall of the Hong Kong International Airport during a demonstration on August 12, 2019.(Photo: Anthony Kwan, Getty Images)

The Hong Kong airport says it will restart flights starting at 6 a.m. Tuesday, according to the Associated Press.

The Associated Press contributed reporting.

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Hong Kong pro-democracy protesters hit the streets for the tenth weekend in a row. Demonstrators used fire extinguishers and a water hose against riot police who fired tear gas into the train station in Kwai Fong and some accused plainclothes officers of disguising as protesters to make arrests.
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